A passerby at the Ideas City street program in the Bowery, New York.
Photograph: José Ginarte/New Museum

Consider the smog meringue. Developed by the Center for Genomic Gastronomy, an artist-led research group that studies relationships between food, culture, ecology and technology, smog meringues supplement the air required to peak sugared egg whites with synthesized, city-specific “atmosphere”. The so-called “London Pea Souper” contains nitrogen oxide, hydrocarbons, dust and sulphur. It’s clever yet inoffensive, with a spicy aftertaste. After I tried it, I sneezed.

“The delegates loved it,” a representative from the center told me, referring to members of the World Health Organisation, where the group recently presented their ideas. “Eating smog is actually better for you than breathing it, because your digestive system is better equipped to handle pollution than your respiratory system.” As the queue at the Center’s stall at New Museum’s biannual Ideas City festival grew steadily, it seemed New Yorkers loved smog meringues, too.

Held across three days, Ideas City presented some 100 events, including conferences, performances, activities and a street fair. The theme of this year’s festival was The Invisible City, after Italo Calvino’s 1972 novel Invisible Cities, in which he wrote that cities, “like dreams, are made of desires and fears, even if the thread of their discourse is secret, their rules are absurd, their perspectives deceitful, and everything conceals something else”.

Ideas City made public space the site of real public engagement with key concerns in contemporary civic life: urban development, citizenship, sustainability, surveillance and what festival director Joseph Grima called “the enduring quest for visibility”. But at times, the experience of Ideas City felt like ingesting smog meringue after smog meringue, with the critical, the complex and the ostensibly “invisible” reconstituted in suspiciously digestible form.

In his keynote address at the festival’s opening conference, Lawrence Lessig argued that when talking about invisibility, we should talk about what is most embarrassing. For Lessig, this is the way surreptitious networks of capital and influence perpetuate inequality in the United States. He argued that political campaign funding constitutes its own primary election, resulting in the average American’s statistically nonexistent impact on public policy.

Big-picture arguments about who or what is invisible can serve to reinforce opacity instead of piercing through it. As nonprofit CEO Rosanne Haggerty pointed out on a panel titled Hope and Unrest in the Invisible City, statistics without specificity reveal very little – and the conference’s most compelling presentations avoided familiar classifications of whole populations. In a panel titled Maps for the Invisible City, moderator Laura Kurgan noted that the word “invisible” is often used to refer to whatever is not visible in data. But visibility can also be a question of navigability or legibility, which are far more slippery, subjective measures.

As part of their week-long residency at the New Museum’s adjacent New Inc space, Deep Lab, a “congress of cyberfeminist researchers”, held a series of free, mostly sold-out events. I attended “Encryption Speed Dating” the morning of day two. The workshop generated educative, if too brief, conversations about online visibility, and how and why to use anonymous browsing and messaging software like Tor. Later in the day, groups of panelists, including the Guardian Project’s Harlo Holmes and Storefront for Art and Architecture’s Eva Franch i Gilabert, offered highly specific explications of the ways issues of race and gender intersect with technology in contemporary surveillance states.

On Ideas City’s third and final day, the clutter of stalls, demonstrations and props gained dimension as fairgoers lost their tentativeness and embarked on lessons in endangered dialects and walking tours about pigeons. I thought about what performance artist Penny Arcade had told the crowd the night before, as part of the festival’s A Performative Conference in Nine Acts: “There are no more empty places.” I wondered if Arcade had yet encountered Foamspace, a “mobile work of architecture” made of enormous geofoam blocks, its white surfaces reflecting glare onto the Bowery sidewalk, shedding tiny pellets – despite clean-up workers’ best efforts – into drain grates.

In contrast to Foamspace, the ETH Future Garden and Pavilion made a sophisticated and convincing argument about the design potential of waste materials. The Pavilion’s catenary arch structure, installed for the duration of the festival in the First Street Garden on Houston Street, was constructed entirely from reusable ReWall panels, held together with newspaper binding and mounted on rented wooden pallets. It wasn’t “mobile” so much as consciously temporary. As ETH Zurich’s Dirk Hebel pointed out, designing with nontraditional materials forces a consideration not only of structural possibilities but of temporality and scale – not everything can, or should, be big; not everything can, or should, last.

Toward the end of Ideas City, I visited a rented Airbnb apartment on Elizabeth Street for the third of three salon-style discussions hosted by art collective AIRBNB Pavilion, presented by New Museum affiliate Rhizome. Crowded onto a bed for a panel titled Hospitality, a group of artists and architects, moderated by sociologist Karen Gregory, discussed the implications and impact of making one’s private space public. The panelists were largely in agreement – on the apparent necessity of Airbnb to offset their living as artists and on the contradictions of monetizing the “personal” – prompting one of them to comment that the conversation was “almost disgustingly hospitable”.

In a way, it was; but it was also one of the more focused and frank discussions of citizenship, visibility and the relationship between space and value that I saw. Its format seemed to underscore the over-valuation of “personal” and “intimate” as frames for public interaction and exchange; the exclusivity of its physical space belied its total accessibility via an online livestream.

Penny Arcade had told her audience that New York is becoming a giant mall – a familiar critique, but also a valid one. The strategy of a mall is to fill all possible space, materializing the desires and fears Calvino spoke of, so that visitors have no option but to engage (or leave). A mall is a site of extreme visibility, and as Ideas City demonstrated both intentionally and not, visibility is not an end in itself. If there are, as Arcade said, no more empty places, “the enduring quest for visibility” means thinking carefully about what we’re doing – and how we’re doing it, and why – when we fill space.